1. Field of the Invention
The present disclosure relates to a method for disposing a microstructure.
2. Description of Related Art
In a typical mounting device, an electric element is grasped and the electric element is mounted on a substrate. Due to downsizing of electric devices, the mounting device is required to grasp a smaller electric element.
However, such a small electric element may be destroyed by small external force. Accordingly, the minimum size of the side length of the electric element which can be mounted with the typical mounting device is approximately 0.2 millimeters.
In order to solve this problem, Patent Literature 1 (U.S. Pat. No. 5,545,291), Patent Literature 2 (Japanese Laid-Open Patent Publication No. Hei 9-120943), and Non-patent Literature 1 (Yeh H.-J. and Smith J. S., IEEE Photonics Technology Letters 6 (1994) 706) disclose methods for disposing electric microelements with use of liquid.
Particularly, Patent Literature 1 and Non-patent Literature 1 disclose methods for disposing GaAs laser diode elements on a substrate. The GaAs laser diode element comprises a side with a length of 20 micrometers.
The methods in the Patent Literature 1 and Non-patent Literature 1 comprise the following steps.
First, the substrate having recesses to which the elements are to be mounted on its surface is formed. The recesses have identical shapes to these of the elements.
Next, the elements to be disposed are dispersed in a liquid such as methanol to prepare a dispersion liquid.
And, the substrate is subjected to the dispersion liquid. Because the recesses have identical shapes to these of the elements, the elements are disposed on the recesses.
Non-patent Literature 2 (Drobac S., Information Display, 11/19 (1999)12) discloses a method for disposing a plurality kinds of elements simultaneously on a substrate by using a liquid.
The method comprises the following steps. First, a plurality of kinds of elements having different shapes are prepared. For example, when three kinds of elements are disposed, circular, triangular, and quadrangular elements are prepared. The plurality of kinds of elements are dispersed in a liquid to prepare a dispersion liquid.
A substrate having recesses having identical shapes to these of respective elements is prepared. The substrate is subjected to the dispersion liquid to dispose the plurality of kinds of elements on the substrate.
Patent Literature 3 (United States Patent Pre-Grant Publication No. 2006/0057293) also discloses a method for disposing a plurality of kinds of elements on a substrate by using a liquid.
The method comprises the following steps. First, a plurality of kinds of elements having identical shapes are prepared. A substrate having a plurality of recesses where the elements are to be disposed is prepared. A lower portion of the respective recesses has a heater.
Next, the substrate is immersed in a liquid. The viscosity of the liquid is increased by heat. The heater heats the lower portion of the recess. This increases the viscosity of the liquid in the neighborhood of the recess.
Subsequently, first elements are dispersed in the liquid. The first elements are not disposed on the recesses covered by the liquid having high viscosity. On the contrary, the first elements are disposed on the recesses which are not heated.
Next, the first elements are removed from the liquid, and the heater is turned off. This decreases the viscosity of the liquid in the neighborhood of the recesses. Furthermore, second elements are dispersed in the liquid to dispose the second elements on the recesses on which the first elements has not been disposed. Optionally, these procedures may be repeated. Thus, the elements are disposed on the recesses of the substrate.